1. Field Of The Invention
The purpose of the subject invention is to provide a data communications network for providing communication of parametric data between microprocessors and/or microcomputers. Although the particular embodiment described grew out of experiences in the automotive environment, such a bus could be adaptable to a variety of non-automotive applications, also. Although the interface integrated circuit developed is capable of supporting many types of higher level communications protocols, such as master-slave or token passing, it is primarily useful in a collision detection network.
2. Description Of The Prior Art
The demand for linking of isolated intelligence incorporated in microprocessors and microcomputers in various stand-alone equipment is well known.
Some solutions used to link the isolated intelligence of microprocessors and microcomputers include Local Area Networks (LAN). LANs link several microprocessors or microcomputers, each of which can take control of the serial data channel and transmit data to any other unit. Some of the problems of LANs are complex protocols, controllers and software, and the need for more complexity in larger systems.
In smaller applications which link several microprocessors or microcomputers within a relatively small area, a much less complex performance than is supplied by a typical LAN is needed to handle the throughput of a small number of microprocessor or microcomputer controlled units.
Known in the art is a digital data bus designed to handle the above-described level of performance. Such a digital data bus system is described in U.S. Pat. No. 4,429,384 to Kaplinsky issued on Jan. 31, 1984, "Communication System Having An Information Bus And Circuits Therefor".
Some of the major differences between the prior art noted above and the subject invention is that the prior art uses speed shifting and the subject invention operates at a constant speed. Another difference is that the prior art utilizes an acknowledged bit from the receiving station whereas the subject invention does not. As such, the subject invention does not require a tight link between the transmitting station and the receiving station(s) which would require that the receiving station(s) respond during a message transmission.
The heart of the subject invention over the prior art is the simplification of the communication link between message transmitter and message receiver.
Another thing added over the prior art to the subject serial data bus, is the interconnection with a serial communication interface (SCI) port.